Preselecting mechanism



March 25, 1941. bAHLSTRQM 2,236,309

PRES-SELECTING Msqmmsu.

Filed March 29, 1940 2 Sh smm 1 @QQM i KJM March 25, 1941. A. DAH LSTROMPRESELECTING MECHANISM 2 Sheoias-Sheet 2 Filed March 29, 1940 j f W KW\w, a w w Z Q n 4 /n v\ M 2 r Patented Mar. 25, 1941 PATENT OFFICEPRESELECTING MECHANISM Arvid Dahlstrom, Chicago, Ill., assignor, bymesne assignments, to Oak Mfg. Co., Chicago, 111., a

corporation of Illinois Application March 29, 1940, Serial No. 326,625

' 2 Claims.

This invention relates to a preselecting mechanism and has particularapplication to the setting of apparatus to a plurality of predetermineddefinite positions lying between two end positions over which theapparatus may be adjusted.

A mechanism of this character finds ready application to a radioreceiver, for example, wherein a turning element such as a gangcondenser is ordinarily adjustable over a predetermined range. Thus inmost instances a gang condenser for a radio receiver may travel over arange of almst-180, the end positions corresponding to maximum andminimum capacitance values hereinafter referred to as full in and outpositions.

As is well known, the response of a receiver is conditioned by theadjustment of the tuning mechanism and particular stations may be chosencorresponding to particular adjustments of the tuning mechanism. In manyinstances, the owner of a receiver is accustomed to tune in frequently asmall number of local stations. As to these stations, it is desirable toprovide a simple means for preselecting the station without manuallyadjusting the condenser to the corresponding position.

In general, the invention is applied to any device having a part whichmay be adjusted to any position over a range extending between two endpositions. Means are provided for biasing the movable part toward oneend position. A head is provided. which is manually set to any one of aplurality of definite on positions or conditions corresponding todefinite positions of the adjustable part. The head also has offpositions or conditions existing during short times between the manualmanipulation of the head to select a position and the assumption of thatposition by the movable part; i. e. during the actual operating cyclebut prior to the actual response when a preselected position has beenestablished.

During an ofi position or condition, the movable part is forced againstits bias toward the other end position. At the on position or conditionof the head, the normal bias of the movable part asserts itself. A stopis provided for 1imit ing the bias response of the movable part toestablish a preselected position of the movable part. By making thestops adjustable, any part position may be established as a preselectedpoint.

Referring to the drawings:

Figure 1 is an isometric view of the preselecting mechanism applied to agang condenser;

Fig. 2 is an end elevation view of the preselecting meansin onepreselected position;

Fig. 3 is a view similar to Fig. 2 but showing the mechanism inpreparation for preselecting a position;

Fig. 4 is a view similar to Fig. 2 but showing the mechanism in adifferent preselected position;

Fig. 5 is a section on line 5-5 of Fig. 2; Fig. 6 is a section on lineii -6 of Fig. 5; and Fig. 7 is an end elevation view of the index means.10

The preselector is shown as operating upon .a gang condenser, the latterconsisting of a base [0 having a series of stator plates II and rotorplates l2 mounted upon a shaft [3 rotatably journalled in base Ill.Rotor plates I2 normally 1 have almost 180 range of travel from an endfull-in to an end full-out position. In the full-in, position strips I!carried by the rotor plates l2 may cooperate with the statorll todetermine a stopping position. In the full-out position, strips I! maystrike against frame Ill 'to determine the other end position. Any otherlimiting means may be used or may be omitted entirely and reliance behad upon the preselector means to determine the range limits. I

Rotors l2 of the gang condenser are biased to one end position by a coilspring l5, one end of which is anchored to the shaft l3 and the otherend of which is anchored to base l0. As shown here, spring l5 tends tomove the rotor plates l2 to a full-out position. Rotor shaft I3 alsocarries a pinion 20 normally meshing with a rack 2| on an arm 22. Arm 22has a pair of aligned elongated slots 23 and 24 along the length thereofadapted to restrain arm 22 against transverse 35 movement but permittinglongitudinal movement thereof. Thus, rotors l2 and arm 22 havecorresponding movements.

Carried by base I0 is a pin 25 fitting in slot 23, the pin beingprovided with a shoulder 26. Slot 24 is provided with a pin 28'mountedbetween spacedbrackets 29 and; 30 carried by condenser base Ill. Pin 28has a sleeve 3| between arm 22 and bracket 29. Between bracket 30 andarm 22 a manual control head 32 is rotatably mounted on pin 28. Thishead consists of a hub 33 and a peripheral flange portion 34 joinedtogether by a radial side portion 35. It will be noted that arm 22 issnugly shouldered between sleeve 31 and head 32.

Carried by flange portion 34 at one side thereof,

. are a plurality of uniformly disposed pins 31.

Cooperating with pins 31 is a dog 40 having a cam surface 4| and carriedby arm 22 in the path of pins 31 so that upon rotation of the head a pinengages the cam surface 4| and depresses dog 40 and arm 4| down to itslowest position as seen in Fig. 3. The direction of rotation of the headin Fig. 3 is clockwise.

It might be noted here that the bias of the gang condenser due to coilspring l5 will tend ,full closed position. When pin 31 has passed camsurface 4! of dog 40, it is clear that the bias of coil spring l5 uponthe rotors l2 oithe gang condenser will tend to move arm 22 upward fromits bottom position. The manual control for determining the preciseposition oi stoppage on this return movement of the gang condenser willnow be described.

Corresponding to each pin 31 there is provided a screw 45 whose tip 45and head 41 are rotatably journalled in hub 33 and fiange portion 34respectively. Peripheral portion 34 is provided with a suitable apertureso that milled head 41 may be reached for turning by a screw driver. A

- spring 48 is disposed around the body of the bolt drawal.

and bears against the inside of the flange portion 34 to retain the boltin position against with- Carried by each bolt 45 is a nut 50 which mayhave a generally triangular shape as shown in Fig. 6 with the base 5inormally bearing against the adjacent surface of radial portion." whilethe tip 52 extends outwardly.

Turning of bolt 45 will cause nut 50 to ride up and down and alter itsdistance from hub 33. A finger 54 carried by the free end of arm 22normally extends into the head interior and cooperates with the undersurface of tip 52 of a nut to function as a stop for upward movement oflever 22.

' The various screws 45 are so disposed angularly with respect to pins31 as to permit a pin 31 to depress arm 22 to its lowest position asshown in Fig. 3 and then, after pin 31 has cleared dog 40, permit coilspring l5 to move the mechanism including arm 22 back until finger 54 isstopped by one of the nuts. At this point the entire mechanism hasreached a preselected position. In

order to index the head, a star-shaped index wheel 60 may be carried byhub'33 near bracket 3|. This index wheel 60 is naturally rotatable withmember and has as many points as the head has screws 45. A roller 5|carried by an arm 62 pivotally mounted at 53 to bracket 3| may be pulledagainst wheel 30 by means oi a coil spring 64 to obtain an index actionfor the head.

If desired, one or more of the screws 35 may have a thumb piece 86 sothat direct manual control is provided rather than through a screwdriver as with the other screws.

Flange portion 34 may have a plurality of ribs or finger pieces 58for'providing a grip for-turning part 35. Suitable clips 10 may beprovided at each bolt head 45 to cover the same and to permit a. card tobe clipped in upon which the name of some radio station may beindicated.

It is to be understood that in the broader aspects of this invention,the head may be any movable meanswhich when operated will first releasethe part to indexed from any previous setting, move said part againstits bias to the end position and then permit said part to respond to thebias and move up to any position determined by the movable means.

It is also to be understood that instead of am moving the movable partagainst its bias to one end position and thereafter permitting saidspring to return the part to a predetermined position,

that the movable part may first be permitted to move toward the otherend position under the influence of the spring and thence the part movedagainst its spring bias toward the stop. To accomplish this, coil springl5 may be made so that it tends to open up and bias the rotor to theposition for maximum capacitance. Then, upon movement of the head, itwill be necessary to pull up finger 54 against the desired stop andmaintain the linger in that position against the bias of coil spring l5,or simply have finger 54 rest against the outer side of stop nut 55.

What is claimed is:

1. A preselector mechanism for apparatus having a part movable over acontinuous range between two end positions, said mechanism comprisingmeans for biasing said part toward one end position, a controlhead'manually adjustable to any one of a plurality of definite onsettings,

each setting corresponding to a preselected partposition, said headhaving an of! setting during the operating cycle of said mechanism priorto the actual response, cooperating means on said head and part formoving said part against its normal bias substantially. to the other endposition automatically upon movement of said head from one on positionto an oil position in preparation for another on position, saidcooperating means only operating during oil position settings of saidhead and releasing said part for bias response when said head hasattained the other on position and means for each on position headsetting for limiting the bias response of said part to determine apreselected position.

' 2. A preselector mechanism for apparatus having a part movable over acontinuous range between two end positions, said mechanism comprisingmeans for biasing said part toward one end position, a rotatable controlhead manually movable from one definite position to another definiteposition in succession and having a plurality oi definite on positionscorresponding. to preselected part positions with intermediate oil!positions for said head, means for moving said part against its biastoward the other end position, said means being inoperative at onpositions of the control head, means on said control head movabletherewith cooperating with said part moving means for operating saidmeans during the movementof said control head from one position to.asucceeding position, and means for limiting the bias response of saidpart to determine a preselected position.

3. A preselector mechanism for apparatus having a part movable over acontinuous range between two end positions, said mechanism comprisingmeans for biasing said part toward one end position, a control headrotatable about an" axis and manually movable to any one of a pluralityof definite positions corresponding to a preselected stop positiQn meanscoupled to said 1 means for movingsaidarm substantially to'an 1 endposition corresponding to movement of said' head axis of rotation andwas corresponding to the control head positions, said stops havingpredetermined distances from said control head axis of, rotation, andmeans on said arm ior'engaging a selected stop upon the return-motion ofsaid' arm.

' 4. A preselect'or mechanism for apparatus having a part movabl'eover acontinuous range between two end positions, said mechanism comprisingvmeans for biasing -said part toward one end position, an-arm movablealong it straight line, means-coupling .lsaid; and said part wherebyboth have corresponding movements,

part against its bias towardth e other-position, means for releasingsaid arm, '9 Permit said part bias to reassert itself, and means forstopping said arm at a preselected point in 'its returntravel-f 5. Apreselector mechanism for apparatus having a part. movable over acontinuous range between two end positions, said mechanism comprisingmeans for biasing said part toward oneend position, an arm movable in astraight line between two end'positions and coupled to'said part so thatthe position 01' said arm corresponds to the position of said part inits range, a control head vmanually movable to any one or a plurality ofdefinite positions corresponding to preselected part positions, means onsaid control head operating when said head is being moved to a newposition for moving said arm substantially to an end positioncorresponding to a movement of said part against its spring biastotheother position, said control head means thereafter reIeas-J ing saidarm to permit end position, an arm movable along a straight line betweentwo end positionasaid am being coupled to said part whereby said M andarm said bias to reassert itself. and means on said control-headfor'stoppingsaid arm at;a -predetermined positiononthe return movementthereof,-

have corresponding motions,- a rotatable control head manually movableto any one of a. plurality of definite positions corresponding topreselected part positions, means onsaid control head for moving saidarm substantially to an end position corresponding to the-other position-oi. said part v againstthe bias thereoffsaid means being operatlveonlywhen said control'head is between two adjacent positions,a'plurality'of stops carried byv 5- said control head, each stopcorresponding toa "head position the radial distance or a stop ,fromthe-axis of rotation of said head-determining the; preselectedpositionotthe part, andmeanson saidarm idr engagingeach stop in successionas;

the control head'jis rotated through successive positions to determinethe return positions of l; A preselector mechanism for apparatus havinga part movable over a continuous range between two end positions, saidmechanism comprising means for biasing said part toward one endposition, an arm movable along a straight line between two end positionsand coupled to said part so that said arm and said part havecorresponding positions, a control head comprising a wheel rotatableabout an axis, said wheel having a plurality or set positions, means onsaid wheel for moving said lever upon wheel movement tojforce said armsubstantially to an end position corresponding 'to the other position orsaid part and against the part bias, said means on said wheel releasingsaid arm when said wheel has reached a deiinitepositicma stop carried bysaid wheel at each position thereof and disposed at a radial distancefrom the wheel center corresponding to a desired preselected partposition,

.said arm line of motion lying in a plane parallel to the plane ofrotation of said wheelr each wheel position being at a point whereawheelradius through a desired stop is parallel to the line or motion orsaid arm, and'means on said lever for engaging said desired stop todetermine the return position or said arm when said part biasreasserts-itseli.

I ABVDDAHLSTROML

